The zinc finger and DHHC domain-containing protein 8 (ZDHHC8) gene is located on chromosome 22q11, which several genome scans have provided repeated evidence for a significant linkage with bipolar disorder (BPD) and schizophrenia. A recent study revealed that a single nucleotide polymorphism (SNP), rs175174, which has potential effects on splicing, in intron 4 of the ZDHHC8 gene is associated with susceptibility to patients with schizophrenia in US and South Africa. We examined three SNPs of the ZDHHC8 gene, including rs175174, by case–control association in Japanese patients with BPD (N=172) and controls (N=298) or patients with schizophrenia (N=407) and controls (N=497). No significant association with BPD or schizophrenia was observed. After stratification by subcategories, bipolar I and II of BPD, and paranoid and disorganized types of schizophrenia, no significant association was found, nor was a significant association with either disorder found after dividing by gender. These data suggest that the ZDHHC8 gene may not be associated with susceptibility to BPD or schizophrenia, at least in a Japanese population.